4.4. Structural peculiarities and environmental input as
arboreal adaptations in P. tricuspis skull evolution
Sanger et al (2011) suggested that similar skull modules in
morphologically related arboreal species lineages have been found to
evolve traits that converge on similar integration patterns as seen in
the long-faced anoles (A. carolinensis and A.
bahorucoensis ) in the evolution of rostrum specific modules and the
short-faced trunk-ground anoles (A. sagrei and A. cybotes )
with no modularity at all. Average asymmetry in the current sample
population seemed to be concentrated in rostral areas, the rostral limit
of the nasal bone as well as the caudal limit of the parietal bone in
the dorsal aspect while the posthion, ventro-lateral sutures of temporal
bones and the zygoma represented major asymmetric areas on the ventral
side. Considering the heterogeneity of the sampling geographical
ecologies; across the rain forest belt and guinea savannah zone this may
disallow putative inference on similar skull developmental errors and
skull asymmetric components observed (Fig. 5).
Our results on modularity of subsisting and contiguous cranial parts
partitioned based on anatomical co relations, embryologic origins
suggested a profoundly stronger covariance coefficients for symmetric
components for all hypothesis tested but a minimal RV coefficients for
asymmetric components (Table 8) as an attestation of a global weakness
of skull integration processes in asymmetry of component parts, an
observation which has been documented for rodents, reptiles, insects and
dogs (Drake and Klingenberg, 2010; Esquerre et al., 2017; Benitez et
al., 2020). Landmark partitions based on the fore going resulted in
lower co-variation in partitions based on developmental relations
comparison to partitions based on anatomical proximities. A combination
of three separate embryological compartments were analyzed for
dependency but was found to be comparatively weaker to all other tested
partitions for dorsal skull landmarks. The reverse was demonstrated in
the ventral view for such hypothetical tests. A caveat could be the
inadequacy of structural landmarks or limitation of assessable modules
to clearly elucidate the boundaries between these partitions.